A very close friend served with Montagnard indigenous forces as a Special Forces advisor (on his second tour) in the mountains of Vietnam. Their weapons were all WW II vintage, being the BAR, Garand, and particularly the M2 Carbine, much liked because of its small size and firepower.. The people are small in stature, and his photos of them carrying the BAR and Garand really illustrate this.
At any rate, their camp came under prolonged attack through one long night, and my friend says he fired over 600 rounds from his Garand without a failure or stoppage of any kind. Photos taken from his position the next morning show a carpet of '06 brass, dozens of empty clips, and VC bodies all over the place. My pal was wounded twice during that fight and has the scars (and those from other battles) to prove it.
My personal (peacetime!) experience with the Garand spans four or five different rifles which I've owned, and if they are properly cared for, they WILL function very reliably. "Proper care" includes good ammunition, of course. Almost all of my Garand work has been with handloads, and even then they are VERY consistent and reliable rifles. This even includes temperatures down to forty below zero. My current M1 has fired hundreds upon hundreds of cast-bullet loads consecutively and reliably without cleaning, as recently as last year. I believe the count on that occasion reached well over 500 rounds before I stripped it just out of curiosity....it was still running just fine!
In the case recounted by RNB, the failure to fire was probably because the bolt hadn't rotated to the fully-locked position. Something about the cartridge was likely incorrect, and the bolt just couldn't lock up correctly.
I've had head separations in several different M1s and M14s, where the base of the case was usually ejected and the next round was a LONG way from chambering as it jammed tightly into the headless case in the chamber. The bolts were about two inches from closed. It's very hard for me to believe that three separated cases could be found in one chamber. DANG, Vern! Not questioning your honesty at all, but I just can't see how it could happen....